1. (1 mark) Given \\ n2m NIN.BEND, then the value of the series 6 E (()(21 - 1)) + 1) is given by: a) N'(N + 1) + 6N b) 2N(N + 1) +6N c) NON + 1)IN+2) + 6N d) N(N - 1) + 6N e) N(N + 1)(2N +1) +6N